@Westbrook

What happens in the time between setting the referenceTarget, via either technique, and that element actual existing due to the innerHTML being set? Should we talk about that in any way?

That's implicitly covered by the fact that reference target is a Live Reference. Basically, the reference target gets updated any time something changes in the DOM that affects it. For example adding elements to the shadow DOM tree by setting innerHTML will update the reference target. It's equivalent to the non-shadow-dom case: if you have <label for="foo">...</label> and then later add <input id="foo"> to the DOM, the label will be "updated" to be for the input.

That said, it might be worth expanding the Live References section to include mentions of the DOM changing, instead of only mentioning the referenceTarget changing. I can make that change in a separate PR.

Added a follow-up PR to clarify the live references: #1067